title: Context and the renewal of conditioned taste aversion: the role of rat dorsal hippocampus examined by electrolytic lesion.
abstract: An extinguished conditioned response can sometimes be restored. Previous research has shown that this renewal effect depends on the context in which conditioning versus extinction takes place. Here we provide evidence that the dorsal hippocampus is critically involved in the representation of context that underscores the renewal effect. We performed electrolytic lesions in dorsal hippocampus, before or after extinction, in a conditioned taste aversion paradigm with rats. Rats that underwent all conditioning, extinction and testing procedures in the same experimental context showed no renewal during testing in the original context. In contrast, rats that underwent extinction procedures in a different experimental context than the one in which they had acquired the conditioned response, showed a reliable renewal effect during testing in the original context. When electrolytic lesion was performed prior to extinction, the context-dependent renewal effect was disrupted. When electrolytic lesion was undertaken after extinction, we observed a complex pattern of data including the blockage of the conventional renewal effect, and the appearance of an unconventional renewal effect. The implications of these results are discussed with respect to current views on the role of the dorsal hippocampus in processing context information.
authors.affiliation: Department of Physiology, Yamagata University School of Medicine, 2-2-2 Iida Nishi Yamagata, Yamagata, 990-9585 Japan ; Tamagawa University Brain Science Institute, Tokyo, 194-8610 Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Kosuke
authors.initials: K
authors.lastname: Sawa
authors.forename: Muneyoshi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Johan
authors.initials: J
authors.lastname: Lauwereyns
authors.forename: Minoru
authors.initials: M
authors.lastname: Tsukada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Aihara
keywords: Conditioned taste aversion; Context; Lesion of dorsal hippocampus; Renewal effect